Related
This question already has answers here:
how to create an alert in a swift file model that works for various view controller
(2 answers)
Closed 4 years ago.
I am trying to create a alert box inside the swift file other than the UIViewController file. but I could not create it.
extension NetworkManager {
func showAlert(message: String,from:UIViewController, title: String = "") {
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
let OKAction = UIAlertAction(title: "OK", style: .default, handler: nil)
alertController.addAction(OKAction)
from.present(alertController, animated: true, completion: nil)
}
}
the above code is for implementing alertcontroller but I don't know how to pass the view controller I need to present so need assistance.
extension UIViewController {
func showAlert(message: String, title: String = "") {
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
let OKAction = UIAlertAction(title: "OK", style: .default, handler: nil)
alertController.addAction(OKAction)
self.present(alertController, animated: true, completion: nil)
}
}
and use like this
from.showAlert(message:"Your message", title: "Title")
Add a Utilities class in your project.
class Utilities {
static func showSimpleAlert(OnViewController vc: UIViewController, Message message: String) {
//Create alertController object with specific message
let alertController = UIAlertController(title: "App Name", message: message, preferredStyle: .alert)
//Add OK button to alert and dismiss it on action
let alertAction = UIAlertAction(title: "OK", style: .default) { (action) in
alertController.dismiss(animated: true, completion: nil)
}
alertController.addAction(alertAction)
//Show alert to user
vc.present(alertController, animated: true, completion: nil)
}
}
Usage:
Utilities.showSimpleAlert(OnViewController: self, Message: "Some message")
Here is the extension I made. It allows to show either Alert or Action sheet and allows multiple actions "from the box"
extension UIViewController {
func presentAlert(title: String?, message: String, actions: UIAlertAction..., animated: Bool = true) {
let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
actions.forEach { alert.addAction($0) }
self.present(alert, animated: animated, completion: nil)
}
func presentActionSheet(title: String?, message: String, actions: UIAlertAction..., animated: Bool = true) {
let alert = UIAlertController(title: title, message: message, preferredStyle: .actionSheet)
actions.forEach { alert.addAction($0) }
self.present(alert, animated: animated, completion: nil)
}
}
Usage
let delete = UIAlertAction(title: "Delete", style: .destructive, handler: { _ in /* Your code here */})
let cancel = UIAlertAction(title: "Cancel", style: .default, handler: nil)
presentAlert(title: .albumPreferencesDeleteAlertTitle, message: "Very important message", actions: delete, cancel)
This is the more generalise method to show alert on view controller
func showAlert(msg: String, inViewController vc: UIViewController, actions: [UIAlertAction]? = nil, type: UIAlertControllerStyle = .alert, title: String = kAppName) {
let alertType: UIAlertControllerStyle = .alert
let alertTitle = kAppName
let alertVC = UIAlertController(title: alertTitle, message: msg, preferredStyle: alertType)
if let actions = actions {
for action in actions {
alertVC.addAction(action)
}
} else {
let actionCancel = UIAlertAction(title: "OK", style: .cancel, handler: nil)
alertVC.addAction(actionCancel)
}
vc.present(alertVC, animated: true, completion: nil)
}
Usage
AppUtilities.showAlert(msg: "Test msg", inViewController: self) //for alert
AppUtilities.showAlert(msg: "Test msg", inViewController: self, actions: [okAction, cancelAction]) //for alert
AppUtilities.showAlert(msg: "Test Msg", inViewController: self, type: .actionSheet) //shows action sheet
You can add this function in extension or create a separate utility class as you want.
I have multiple view controllers in my application. And in each of them I have to show alerts based on some conditions. Instead of adding alert controllers in each of them, I tried using inheritance as follows.
UIExtension.swift
class UIExtension: UIViewController {
func prepareAlert(title: String, message: String) -> UIAlertController {
let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Ok", style: .default, handler: nil))
return alert
}
}
FirstViewController.swift
class FirstViewController: UIExtension {
//somewhere inside used the following
present(prepareAlert(title: "Error Validation", message: "invalid fields"), animated: true, completion: nil)
}
Similarly, used UIExtension in other viewcontrollers to show alerts. Is this way recommended?
For something like this, you are better off adding your prepareAlert method to a UIViewController extension. No subclassing required.
extension UIViewController {
func prepareAlert(title: String, message: String) -> UIAlertController {
let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Ok", style: .default, handler: nil))
return alert
}
}
Then your view controller:
class FirstViewController: UIViewController {
//somewhere inside used the following
present(prepareAlert(title: "Error Validation", message: "invalid fields"), animated: true, completion: nil)
}
This allows you to use prepareAlert from any view controller include UITableViewController, UICollectionViewController, etc.
The approach is technically correct, although if you consider extending all UIViewController instances, regardless of any conditions, then it's more handy to extend it directly:
extension UIViewController {
func prepareAlert(title: String, message: String) -> UIAlertController {
let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Ok", style: .default, handler: nil))
return alert
}
}
rmaddy was faster. But I decided not to delete the answer, but add another idea.
Another approach is to use protocol as a wrapper for certain functionality, and this is also widely used.
Say, you have a protocol, associated with some functionality, like generating alert, in this case:
protocol Alertable {} // or whatever else name
extension Alertable {
func prepareAlert(title: String, message: String) -> UIAlertController {
let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Ok", style: .default, handler: nil))
return alert
}
}
Then, whenever you want certain UIViewController instance (or any other class, you get the idea) to be associated with this functionality, simply do:
class FirstViewController: UIViewController, Alertable {
// Now you can do the same:
present(prepareAlert(title: "Error Validation", message: "invalid fields"), animated: true, completion: nil)
}
To sum up, making up a protocol and extending it, and then associating certain classes with it - to expose that functionality - is a very handy and useful practice. In particular, this is a good way to encapsulate some functionality, for example, if you don't mean global/class-wide access to it.
Some extension method I am sharing with you that is used frequently in most application you can use it in any where of UIViewController class and enjoy :)
extension UIViewController {
let kAPPNAME = "Your App name"
func showOkAlert(_ msg: String) {
let alert = UIAlertController(title:
kAPPNAME, message: msg, preferredStyle: .alert)
let okAction = UIAlertAction(title: "OK", style: .default, handler: nil)
alert.addAction(okAction)
present(alert, animated: true, completion: nil)
}
func showOkAlertWithHandler(_ msg: String,handler: #escaping ()->Void){
let alert = UIAlertController(title: kAPPNAME, message: msg, preferredStyle: .alert)
let okAction = UIAlertAction(title: "OK", style: .default) { (type) -> Void in
handler()
}
alert.addAction(okAction)
present(alert, animated: true, completion: nil)
}
func showAlertWithActions(_ msg: String,titles:[String], handler:#escaping (_ clickedIndex: Int) -> Void) {
let alert = UIAlertController(title: kAPPNAME, message: msg, preferredStyle: .alert)
for title in titles {
let action = UIAlertAction(title: title, style: .default, handler: { (alertAction) in
//Call back fall when user clicked
let index = titles.index(of: alertAction.title!)
if index != nil {
handler(index!+1)
}
else {
handler(0)
}
})
alert.addAction(action)
}
present(alert, animated: true, completion: nil)
}
func showOkCancelAlertWithAction(_ msg: String, handler:#escaping (_ isOkAction: Bool) -> Void) {
let alert = UIAlertController(title: kAPPNAME, message: msg, preferredStyle: .alert)
let okAction = UIAlertAction(title: "OK", style: .default) { (action) -> Void in
return handler(true)
}
let cancelAction = UIAlertAction(title: "Cancel", style: .cancel) { (action) -> Void in
return handler(false)
}
alert.addAction(cancelAction)
alert.addAction(okAction)
present(alert, animated: true, completion: nil)
}
}
USES
class FirstViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
//Only Info
self.showOkAlert("Hello")
//Info with Okay button
self.showOkAlertWithHandler("Hello Again") {
print("Tap to Okay")
}
//Show alert with Okay and cancel
self.showOkCancelAlertWithAction("Hello with Cancel") { (isOk) in
if isOk {
print("Okay")
}
else {
print("Cancel")
}
}
//Show alert with actions
self.showAlertWithActions("Hello with action", titles: ["Allow","Don't Allow", "Cancel"]) { (tapIndex) in
if tapIndex == 1 {
print("Allow")
}
}
}
}
I am new of swift3. Now, I am finding a way to call alert function from other swift.file
Like this:
//MainView.swift
//Call function
AlertFun.ShowAlert(title: "Title", message: "message..." )
//Another page for storing functions
//Function.swift
public class AlertFun {
class func ShowAlert(title: String, message: String ) {
let alert = UIAlertController(title: tile, message: message, preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.default, handler: nil))
self.present(alert, animated: true, completion: nil)
}
}
Problem in here...Cannot do this in this way....
self.present(alert, animated: true, completion: nil)
How can I implement it? Thanks.
Pass the viewController reference as a parameter to the showAlert function like:
//MainView.swift
//Call function
AlertFun.ShowAlert(title: "Title", message: "message...", in: self)
//Another page for storing functions
//Function.swift
public class AlertFun {
class func ShowAlert(title: String, message: String, in vc: UIViewController) {
let alert = UIAlertController(title: tile, message: message, preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.default, handler: nil))
vc.present(alert, animated: true, completion: nil)
}
}
Call Method for your controller
Utility.showAlertOnViewController(targetVC: self, title: "", message:"")
Your Class
class Utility: NSObject {
class func showAlertOnViewController(
targetVC: UIViewController,
title: String,
message: String)
{
let alert = UIAlertController(
title: title,
message: message,
preferredStyle: UIAlertControllerStyle.alert)
let okButton = UIAlertAction(
title:"OK",
style: UIAlertActionStyle.default,
handler:
{
(alert: UIAlertAction!) in
})
alert.addAction(okButton)
targetVC.present(alert, animated: true, completion: nil)
}
}
I found that none of the examples I've seen will work without getting the warning:
Attempt to present <UIAlertController: 0x7f82d8825400> on <app name> whose view is not in the window hierarchy!
The code that works for me is as follows. The function call is as before:
AlertFun.ShowAlert(title: "Title", message: "message...", in: self)
However, to make this work, the Function.swift file has to display the alert inside the DispatchQueue.main.async. So the Function.swift file should look like this:
public class AlertFun
{
class func ShowAlert(title: String, message: String, in vc: UIViewController)
{
DispatchQueue.main.async
{
let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertController.Style.alert)
alert.addAction(UIAlertAction(title: "Ok", style: UIAlertAction.Style.default, handler: nil))
vc.present(alert, animated: true, completion: nil)
}
}
}
Hello I have a utility class in which I have declared AlertViewFunction like this
func displayAlertMessage(userMessage: String,//controller){
let myAlert = UIAlertController(title: "Alert", message: userMessage, preferredStyle: UIAlertControllerStyle.Alert);
let okAction = UIAlertAction(title: "Ok", style: UIAlertActionStyle.Default, handler: nil)
myAlert.addAction(okAction);
self.presentViewController(myAlert, animated: true, completion: nil)
}
The problem is I can't use self here
self.presentViewController(myAlert, animated: true, completion: nil)
I want to pass a controller to this function so I can use like this
controller.presentViewController(myAlert, animated: true, completion: nil)
How Can I pass a controller from any ViewController. Lets say If I am in LoginViewController
Utility().displayAlertMessage(Message.INTERNETISNOTCONNECTED,//controller)
Utility().displayAlertMessage(Message.INTERNETISNOTCONNECTED, controller: self)
and
func displayAlertMessage(userMessage: String, controller: UIViewController)
{
controller?.presentViewController(myAlert, animated: true, completion: nil)
}
pass in the view controller as an argument to the function.
func displayAlertMessage(controller: UIViewController, title: String, message: String?) {
let alert = UIAlertController(title: title, message: message, preferredStyle: .Alert)
let okAction = UIAlertAction(title: "Ok", style: .Default, handler: nil)
alert.addAction(okAction)
controller.presentViewController(alert, animated: false, completion: nil)
}
Alternatively you can even return the alert to the caller of the function for further customization by saying:
func displayAlertMessage(title: String, message: String?) -> UIAlertController {
let alert = UIAlertController(title: title, message: message, preferredStyle: .Alert)
let okAction = UIAlertAction(title: "Ok", style: .Default, handler: nil)
alert.addAction(okAction)
return alert
}
class controller: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let alert = displayAlertMessage("title", message: nil)
presentViewController(alert, animated: true, completion: nil)
}
}
I have various controllers in my app that all require validation, and when validation fails, I want to display an alert with the errors. Is there some best practice/design pattern for doing this? I could simply create a static function in a Helper class like so:
static func displayAlert(message: String, buttonTitle: String, vc: UIViewController)
{
let alertController = UIAlertController(title: "", message: message, preferredStyle: .Alert)
let okAction = UIAlertAction(title: buttonTitle, style: .Default, handler: nil)
alertController.addAction(okAction)
vc.presentViewController(alertController, animated: true, completion: nil)
}
But then I need to pass the view controller..which seems like bad practice. I could shoot off a notification and observe it, but that seems like overkill. Am I overthinking this, or is there some more acceptable way to go about handling something like this?
I ended up creating an extension for UIViewController and creating the alert function there:
extension UIViewController {
func alert(message: String, title: String = "") {
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
let OKAction = UIAlertAction(title: "OK", style: .default, handler: nil)
alertController.addAction(OKAction)
self.present(alertController, animated: true, completion: nil)
}
}
Swift 4
I wanted this same functionality for myself, so I made a full extension. To use it, create a new swift file in your project and name it whatever you'd like. Place the following code inside:
import UIKit
extension UIViewController {
func presentAlertWithTitle(title: String, message: String, options: String..., completion: #escaping (Int) -> Void) {
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
for (index, option) in options.enumerated() {
alertController.addAction(UIAlertAction.init(title: option, style: .default, handler: { (action) in
completion(index)
}))
}
self.present(alertController, animated: true, completion: nil)
}
}
To use it (which so many people don't actually show, which can lead to confusion for a newbie like myself):
presentAlertWithTitle(title: "Test", message: "A message", options: "1", "2") { (option) in
print("option: \(option)")
switch(option) {
case 0:
print("option one")
break
case 1:
print("option two")
default:
break
}
}
As original answer from itstrueimryan at https://stackoverflow.com/a/30714429/6822183
Update for Swift 3:
extension UIViewController {
func alert(message: String, title: String = "") {
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
let OKAction = UIAlertAction(title: "OK", style: .default, handler: nil)
alertController.addAction(OKAction)
self.present(alertController, animated: true, completion: nil)
}
}
I may have found a better answer to this problem, via an article by Krakendev: https://krakendev.io/blog/subclassing-can-suck-and-heres-why.
The idea is to use protocol-oriented programming to create a default implementation of an alert just for UIViewControllers:
protocol Alertable {
func issueAlert()
}
extension Alertable where Self: UIViewController {
func issueAlert() {
// alert code here
}
}
Now, just like that, every UIViewController that adheres to Alertable will have the issueAlert() method available to them without even having to define its own implementation.
And, of course, we can define parameters for the issueAlert function as well:
extension Alertable where Self: UIViewController {
func issueAlert(title: "Default Title", message: String = "Default Message") {
// alert code here
}
}
So our view controller can do either:
issueAlert()
or
issueAlert(title: "Error", message: "Something went wrong")
Two advantages to this approach that I can think of are that you know if a view controller has access to this method just by looking at the Alertable protocol in the class definition, and individual view controllers can override this method if they want to provide custom functionality. Of course, now you can also specify the Alertable contract as a method parameter.
Answer from Sigex is completely fine, except the int indices passing to trace the button clicks might not make sense because, caller needed to keep track with int value. In that case passing string arguments and comparing them in switch case in completion block makes more sense to me. I would rather use like,
import UIKit
extension UIViewController {
func presentAlertWithTitle(title: String, message: String, options: String..., completion: #escaping (String) -> Void) {
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
for (index, option) in options.enumerated() {
alertController.addAction(UIAlertAction.init(title: option, style: .default, handler: { (action) in
completion(options[index])
}))
}
self.present(alertController, animated: true, completion: nil)
}
}
And test with,
class TestViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
presentAlertWithTitle(title: "Test", message: "A sample message", options: "start", "stop", "cancel") { (option) in
print("option: \(option)")
switch(option) {
case "start":
print("start button pressed")
break
case "stop":
print("stop button pressed")
break
case "cancel":
print("cancel button pressed")
break
default:
break
}
}
}
}
Why not create a Utility function that returns the AlertView to the ViewController?
self.presentViewController(Utilities.createAlertController("errorMessage"), animated: true, completion: nil);
Updated for swift 3:
if you want to show the alert message to user used below simple lines of code;
// function defination:
func showMessageToUser(title: String, msg: String) {
let alert = UIAlertController(title: title, message: msg, preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.default, handler: nil))
self.present(alert, animated: true, completion: nil)
}
//function call :
self.showMessageToUser(title: "Alert", msg: "your message to user")
// Enjoy coding..!
I used Sigex's extension in my code, however I have added a check, if options were used or not.
If no options are given in the call, then the Alert only shows "OK" and completes with returning option 0.
extension UIViewController {
func presentAlertWithTitle(title: String, message: String, options: String..., completion: #escaping (Int) -> Void) {
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
if options.count == 0 {
let OKAction = UIAlertAction(title: "OK", style: .default, handler: { (action) in
completion(0)
})
alertController.addAction(OKAction)
} else {
for (index, option) in options.enumerated() {
alertController.addAction(UIAlertAction.init(title: option, style: .default, handler: { (action) in
completion(index)
}))
}
}
self.present(alertController, animated: true, completion: nil)
}
}
Just omit the part , options: "1","2" then default alert is shown.
I love Sigex's extension, but I spiced it up a bit to add style on button depending on the title
func presentAlertWithOptions(title: String, message: String, options: String..., completion: #escaping (Int) -> Void) {
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
if options.count == 0 { //if there is no options, show a basic alert
let OKAction = UIAlertAction(title: "OK", style: .default, handler: { (action) in
completion(0)
})
alertController.addAction(OKAction)
} else { //alert with options
for (index, option) in options.enumerated() {
var alertStyle = UIAlertAction.Style.default
switch option { //check if we should style the buttons
case "Cancel": //cancel style
alertStyle = .cancel
case "Logout", "Discard Changes", "Discard", "Delete", "Remove": //destructive style
alertStyle = .destructive
default: break //keep as default
}
alertController.addAction(UIAlertAction(title: option, style: alertStyle, handler: { (action) in
completion(index)
}))
}
}
self.present(alertController, animated: true, completion: nil)
}
Swift 4.1
let alert = UIAlertController(title: "Atenção",message: "Mensagem Aqui",preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "Ok", style: .default, handler: nil))
self.present(alert, animated: true)